Preparation and MRI performance of a composite contrast agent based on palygorskite pores and channels binding effect to prolong the residence time of water molecules on gadolinium ions.

Herein, gadolinium tannate was simply and conveniently coated on the surface of palygorskite by in situ reaction of a coordination polymer formed between tannic acid and Gd3+. The palygorskite-tannate gadolinium-polyvinyl alcohol integrated composite (PAL@Gd@PVA) is successfully prepared after the introduction of polyvinyl alcohol onto the palygorskite-tannate gadolinium. The structure is characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy analysis. The results show that TA-Gd and PVA are successfully loaded on the surface of palygorskite, and the rod crystal structure of palygorskite in the composite remains intact. Palygorskite fibres constitute the framework of the composite and play a key role in supporting and crosslinking the composite. The prepared compounds showed negligible cytotoxicity and low haemolysis rate, showing good biocompatibility. In vitro MRI results showed that the longitudinal and transverse relaxation rates of the composite are 59.56 and 340.81 mm-1 s-1, respectively.

Exploring the optimal crop planting structure to balance water saving, food security and incomes under the spatiotemporal heterogeneity of the agricultural climate.

Crop planting provided foods, generated incomes, and consumed water resources to different extents under different spatiotemporal agroclimatic conditions. For balancing three aspects, targeting the rice, maize, wheat, and sorghum planted in Liaoning during the recent two decades, we established an integrated research framework consisting of water footprint (WF) accounting, clustering analysis, and fuzzy optimization programming to quantify the temporal trends and spatial distribution of water footprints, and optimized the planting structure under the different spatiotemporal agroclimatic conditions. Results showed that the maximum water footprint differences were 4166.73 m3/t and 4790.71 m3/t in spatial distribution and temporal series, respectively. Based on precipitation, we established 12 agroclimatic scenarios according to K-Means clustering. The fuzzy optimization result indicated that the planting area percent ranges of maize, wheat, rice, and sorghum in Liaoning province were 4.96%-98.62%, 0.00%-8.55%, 0.00%-18.18%, and 0.00%-95.04%, respectively under the different spatiotemporal conditions. This study's methods and results help make targeted decisions related to grain planting structure while considering the complex spatial-temporal conditions.

All-Solution-Processed Multilayered White Polymer Light-Emitting Diodes (WPLEDs) Based on Cross-Linked [Ir(4-vb-PBI)2(acac)].

All-solution-processed multilayered white polymer light-emitting diodes (WPLEDs) are promising candidates for low-cost and large-area flexible full-color flat-panel displays and solid-state lighting. However, it is still challenging to improve their performance. In this work, based on an elegant strategy of orthogonal materials, the utilization of the cross-linked Ir3+ polymer film poly(NVK-co-[Ir(4-vb-PBI)2(acac)]-co-NVK) (NVK = N-vinyl-carbazole; 4-vb-HPBI = 1-(4-vinylbenzyl)-2-phenyl-1H-benzo[d]imidazole; and Hacac = acetylacetone) as the emitting layer (EML) between a hydrophilic polymer film poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole injection layer (HIL) and a hydrophobic polymer film poly(vinyl-PBD) (vinyl-PBD = 2-(4-(tert-butyl)phenyl)-5-(4'-vinyl-[1,1'-biphenyl]-4-yl)-2,5-dihydro-1,3,4-oxadiazole) as the electron transport layer (ETL) led to the successful fabrication of reliable all-solution-processed multilayered WPLEDs. The device exhibits a ηCEMax of 18.19 cd/A, a ηPEMax of 8.16 lm/W, and a ηEQEMax of 9.32% with stable white light (Commission International De L'Eclairage (CIE) coordinates x = 0.269-0.283, y = 0.317-0.330; corrected color temperatures (CCTs) of 7237-8199 K, and CRIs (color rendering indices) of 63-72) under a wide applied-voltage range. Its high performance, especially with record efficiencies among those of reported all-solution-processed WPLEDs, renders cross-linked Ir3+ polymers a new platform to all-solution-processed multilayered WPLEDs.

Efficient white polymer light-emitting diodes (WPLEDs) based on covalent-grafting of [Zn2(MP)3(OAc)] into PVK.

Thanks to the straightforward white light of single grafting-type polymers based on earth-abundant Zn(ii)-complexes, producing cost-effective flexible WOLEDs/WPLEDs with good device performance remains a formidable challenge. Herein, by using the polymer Poly(NVK-co-[Zn2(MP)3(OAc)]) with excellent physical properties for single-layer WPLEDs, record-high efficiencies (η Max c = 13.0 cd A-1, η Max p = 6.1 lm W-1 and η Max EQE = 9.2%) and low (ca. 25%) efficiency roll-off compared to previous organo-Zn2+-based WOLEDs/WPLEDs are realized. This finding renders single Zn(ii)-complex-grafted polymers a new route to low-cost and large-area flexible WPLEDs for potential full-colour flat displays.

Rapid Determination of Ochratoxin A in Grape and Its Commodities Based on a Label-Free Impedimetric Aptasensor Constructed by Layer-by-Layer Self-Assembly.

A simple and sensitive label-free impedimetric aptasensor for rapid determination of ochratoxin A (OTA) has been developed, which was based on the combination between thiolated aptamer and gold nanoparticles by layer-by-layer self-assembly. Because of the interaction between aptamer and OTA, the relative normalized electron-transfer resistance (ΔRct) values obtained by electrochemical impedance spectroscopy (EIS) was proportional to the concentration of OTA and showed a good linear relationship from 0.1 to 10.0 ng/mL, with a lower detection limit (0.030 ng/mL) than one-step thiolated DNA aptasensor. The established method was successfully applied to detect and analyze OTA in table wine and grape juice, and the recovery was 90.56%⁻104.21% when PVP effective removed of phenolic substances. The label-free impedimetric aptasensor was used for rapid detection and quantitation of OTA in the inoculated grapes with the Aspergillus Nigri (H1), and the production of OTA (62.4 µg/kg, 20 µg/kg) far exceeded the maximum levels of 2 µg/kg after inoculation for three days. The developed method exhibited a good specificity, high sensitivity, time-efficient, and it could be applied to detect the OTA concentration in grape and its commodities.

Linear PVA-DTPA-Gd conjugate for magnetic resonance imaging.

In this study, we report the preparation and characterization of the PVA-DTPA-Gd conjugate as a potential MRI contrast agent (CA). The r 1 value and the r 2/r 1 ratio were about 5.6 mM-1 s-1 and 1.31, respectively. In vitro toxicity studies not only demonstrated that the polymeric system possessed good biocompatibility, but also proved that the conjugate could be an attractive candidate for CA.